vector iterators incompatible with const vector&

Question

I\'m writing program for graphs. In this program I have a method which has to return vertices inside the weak component originating at vertex. I am getting: Error \"vector itera

Answer 1

Since you are taking g as a const graph&, this means g.gr is treated as const inside your function. begin on a const vector<T> returns a const_iterator. (also you used == instead of = for assignment)

for (std::vector<int>::const_iterator j = g.gr[hodn].begin(); ...)

But with C++11 or newer you may as well use auto to avoid this

for (auto j = g.gr[hodn].begin(); ...)

or a range-based for:

for (auto&& e : g.gr) {
    if (!used[e]) {
        s.push(e);
        ret.push_back(e);
    }
}